48 STERILIZATION. 
injured by dry heat. The oven of an ordinary gas- 
stove into which a thermometer can be inserted 
makes an excellent hot-air sterilizer. 
(a) Wash thoroughly, using, if necessary, the 
cleaning mixture recommended on page 14, all 
FIGs. 24, 25.—Autoclaves for rapid sterilization by steam 
under pressure. 
flasks, test-tubes, Petri dishes, etc., to be used in 
the preparation of culture-media. 
(4) Plug the flasks and test-tubes with cotton.! 
1“ Sliver’? obtained from cotton-mills is excellent for 
plugging test-tubes, etc. 
